Methanation reactor and method

ABSTRACT

The present relates to a chemical reactor comprising a catalyst bed enclosed in a reactor vessel and at least one cooling tube placed in the reactor vessel and passing through the catalyst bed, characterized in that the cooling tubes are disposed within the reactor so as to generate thermal gradients of at least 20° C./cm thereby generating hot spots throughout the reactor upon carrying out a reaction. The invention further relates to a methanation process.

TECHNICLA FIELD

The present invention relates to a chemical reactor and a thermalmanagement system maximizing the conversion of the Sabatier reaction.The invention further relates to a process for the synthesis ofhydrocarbons from hydrogen and carbon dioxide, in particular by Sabatierreaction.

BACKGROUND OF THE ART

The chemical reactions and processes that allow producing synthetichydrocarbons from hydrogen and carbon dioxide have the potential to playan important role in the energy turnaround. The Sabatier reaction isespecially interesting as it produces methane with a high selectivity,which can be directly integrated in the existing natural gasinfrastructure.

The methanation reaction was first discovered by the French chemist PaulSabatier at the beginning of the 20^(th) century. The reaction describesthe production of methane and water from hydrogen and carbon dioxide, asshown in equation ((1) below:

CO₂+4H₂⇄CH₄+2H₂O_((l))

ΔH _(R) ⁾=−252.8 kJ/mol

ΔS _(R) ⁰=−409.9 J/mol−K   (1)

As shown, this process is highly exothermic, with a reaction enthalpy of−252.8 kJ/mol at standard conditions (T=273.15K, p=1.013.105 Pa).Because of this, the thermodynamic equilibrium conversion is shifted tothe reactant side at higher temperature. FIG. 1 shows the maximalequilibrium conversion as a function of the temperature and at differentpressures, and one can see that high conversion rates can only beachieved at low temperatures.

On the other hand, the kinetics of the reaction follow the Arrhenius lawwhich means that the rate of reaction increases exponentially with thetemperature, as shown in equation ((2) below and in FIG. 2.

$\begin{matrix}{k_{f} = {k_{0}e^{({- \frac{E_{\alpha}}{RT}})}}} & (2)\end{matrix}$

Thus, there is a problem arising in this chemical reaction that twocompeting trends have to be balanced: a higher temperature enables afaster reaction, but the thermodynamic conversion is limited, while alower temperature limits the reaction rate but allows for a highthermodynamic equilibrium conversion.

In order to solve this technical problem, different types of reactorhave been designed to improve the reaction yield. Today, there basicallyexist two main reactor designs: tube reactors and plate reactors. Ingeneral, both cases emphasize on how to minimize the temperaturegradients within the reactor in order to reach an isothermal operation.

For example, document DE102014010055A1 discloses a methanation reactorcomprising a two-phase cooling system and a process to control thetemperature of the system and remove the heat of reaction by boiling acooling medium. However, this document is silent regarding any referenceto maintaining a specific temperature profile within the reactor inorder to maximize the conversion.

Another document, DE102014011274 presents a heat exchanger design for achemical reactor, and especially for a methanation reactor, thatconsists of plates welded together, and a circulating cooling medium inthe space between the plates. A thermal coupling between the coolingmedium and the gas products is thereby achieved and the temperature canbe maintained accurately but there is no mention of maintaining aspecific temperature profile within the reactor in order to maximize theconversion.

In view of the above, a primary object of the invention is to solve theabove-mentioned problems and more particularly to provide a methanationreactor designed and adapted to provide and maintain a specifictemperature profile within the reactor in order to maximize the Sabatierconversion, or any other exothermic reaction.

SUMMARY OF THE INVENTION

The above problems are solved by the present invention.

A first aspect of the invention is a chemical reactor comprising acatalyst bed enclosed in a reactor vessel and at least one cooling tubeplaced in the reactor vessel and passing through the catalyst bed,characterized in that the cooling tubes are disposed within the reactorso as to generate thermal gradients of at least 20° C./cm therebygenerating hot spots throughout the reactor upon carrying out areaction.

According to a preferred embodiment of the present invention, thecatalysts comprise at least one of Nickel, Cobalt and Ruthenium basedcatalysts.

Advantageously, the catalysts comprise 20% wt. Ni/Al₂O₃ or 3% wt.Ru/Al₂O₃.

According to a particular aspect, when the catalyst comprises Nickelloading on alimuna, the nickel loading may vary from 1 to about 20% wt.

According to another particular aspect, when the catalyst comprisesruthenium loading on alimuna, the ruthenium loading may vary from 0.25to about 3% wt, (e.g. 05% wt Ru).

Preferably, the chemical reactor comprises at least two cooling tubes.

According to a preferred embodiment of the present invention, theminimal distance between the tubes is not less than 1.5 times the tubediameter.

Advantageously, the minimal distance between the tubes is not less than2 times the tube diameter.

Preferably, the temperature of the cooling medium is different in thedifferent tubes.

According to a preferred embodiment of the present invention, the tubesare fed with a cooling medium such as water, oil or any other fluidsuitable for this purpose.

Advantageously, the thermal gradients is at least 100° C./cm

Preferably, the temperature gradients are controlled by controllingeither the space velocity of the inlet reactant gases and/or the flowrate of the cooling medium.

According to a preferred embodiment of the present invention, thechemical reactor comprises a thermal management system adapted to removethe heat from the reaction zone and to control the temperature of thechemical reactor.

According to a preferred embodiment of the present invention, thereactor is adapted for an exothermic chemical reaction.

According to another aspect, is provided a method of production ofmethane from hydrogen and carbon dioxide (Sabatier reaction) comprisingthe steps of:

-   -   a) Providing a chemical reactor comprising a reaction chamber        which comprises a gas loading zone and a catalyzed reaction zone        comprising a catalyst bed;    -   b) Loading a reaction gas mixture of hydrogen and carbon dioxide        in the gas loading zone of the reaction chamber, such that the        gas pressure in the reaction chamber is between about 1 and 20        bar (e.g. 5 bar);    -   c) Heating the reaction chamber, in particular the catalyst bed        at a temperature between about 220 and about 260° C. such that        the Sabatier reaction and a gas flow through the catalyst bed        start;    -   d) Creating a temperature gradient of about 100° C. within the        reaction chamber and in particular within the catalyst bed by        cooling the catalyst bed with a cooling system directly        integrated in said catalyst bed;    -   e) Collecting the resulting gas mixture (methane and water)        flowing through the catalyst bed.

The particular advantages of this device of the invention are to solvethe technical problem identified above.

BRIEF DESCRIPTION OF THE DRAWINGS

Further particular advantages and features of the invention will becomemore apparent from the following non-limitative description of at leastone embodiment of the invention which will refer to the accompanyingdrawings, wherein

FIG. 1 represents the Thermodynamic equilibrium conversion as a functionof the temperature at different pressures;

FIG. 2 represents the kinetics of CO₂ methanation as a function of thetemperature;

FIG. 3 schematically represents a first embodiment of the methanationreactor;

FIG. 4 schematically represents an experimental CO₂ conversion atdifferent temperatures and space velocities;

FIG. 5 schematically represents the experimental setup for themethanation reactor;

FIG. 6 schematically represents a calculated temperature distribution inthe cross-section of the methanation reactor (FEA Simulation).

DETAILED DESCRIPTION OF THE INVENTION

The present detailed description is intended to illustrate the inventionin a non-limitative manner since any feature of an embodiment may becombined with any other feature of a different embodiment in anadvantageous manner.

Disclosed herein is a methanation reactor system including a reactorvessel comprising a housing defining a reaction chamber comprising a gasloading zone and a catalyzed reaction zone; a cooling system; a gas flowsystem; a heating element in the vicinity of the reaction chamber; atemperature sensing system and a temperature management system, thecatalyzed reaction zone of the reaction chamber comprises a catalystbed, the cooling system comprises a plurality of coolant circulationlines within the catalyst bed, the gas flow system comprises a reactiongas feeding system configured to load reaction gases into the loadingzone of the reaction chamber and a reaction gas exhaust system toexhaust reacted gases through the catalyst bed which is thermo-regulatedby the heating element and the cooling system under the control of thetemperature management system.

The gas flow system allows loading the reaction gases (e.g. H₂ and CO₂,preferably a mixture thereof) within the gas loading zone of thereaction chamber through a reaction gas feeding system comprisingpressure regulating elements and exhausting the reacted gases (e.g. CH₄and water vapor) from the catalyzed reaction zone of the reactionchamber through a reaction gas exhaust system comprising pressureregulating elements. The gas flow system my further comprise a purge gasfeeding system and a purge gas exhaust system to flush purge gases (e.g.He, N₂) through the reactor chamber for purging the reaction chamber orcalibrating the gas flow.

The heating element allows elevating the temperature of reaction chamberto a temperature at which the methanation reaction starts between thereaction gases within the gas loading zone of the reaction chamber.

The cooling system allows decreasing the temperature of the reactionchamber, in particular within the catalyzed zone, while the methanationreaction proceeds, thereby creating a temperature gradient within thecatalyzed reaction zone, in particular within the catalyst bed.Typically, the thermal gradient within the catalyst bed is at least 100°C./cm.

The cooling system comprises a cooling inlet for the coolant (e.g.water, oil or other cooling medium) flow, a coolant circulation line, acoolant outlet and a coolant flow controlling means. The coolantcirculation line advantageously comprises a plurality of coolantcirculation channels (e.g. tubes) embedded in the reaction chamber andpassing through the catalyst bed. The cooling system advantageouslycomprises a coolant exhaust system to allow controlling the cooling linepressure and maintaining its pressure lower than 5 bar, typically lowerthan 1.5 bar.

The temperature sensing system comprises temperature sensing elements invarious positions of the methanation reactor system, comprising thecooling system (inlet and out lets) and the reaction chamber, inparticular the catalyst bed to monitor the temperature of the reactionchamber during the methanation reaction.

The temperature management system 5 allows regulating the temperature ofthe reaction chamber by regulating the temperature of the coolantentering the cooling system 14 though the cooling inlet 23 and its flowrate through the coolant circulation line(s) 25 and/or the flow spacevelocity of the reaction gases by regulating the flow rate of thereaction gases from the reaction gas feeding system 17 into the gasloading zone of the reaction chamber 12.

According to a particular aspect, the methanation reactor system furthercomprises a condenser system on or after the reaction gas exhaust systemto eliminate water by condensation from the reacted gases.

FIG. 3 shows a first embodiment of the methanation reactor of thepresent invention which is a chemical reactor for exothermic chemicalreaction occurring in the gas phase on a heterogeneous catalyst. Thecooling system of the reactor is arranged such that high thermalgradients are present within the reactor, favoring high equilibriumconversion and fast reaction rate simultaneously.

Referring to FIG. 3, a methanation reactor system 1 according to anembodiment of the invention comprises a reactor vessel 2 comprising ahousing 10 defining a reactor chamber 12 comprising a gas loading zone18 and a catalyzed reaction zone 20; a cooling system 14; a gas flowsystem 15; a heating element 3 in the vicinity of the reactor chamber12; a temperature sensing system 4 and a temperature management system5, the catalyzed reaction zone of the reactor chamber comprises acatalyst bed 21, the cooling system comprises a plurality of coolantcirculation lines 25 within the catalyst bed, the gas flow system 15comprises a reaction gas feeding system 17 configured to load reactiongases into the loading zone of the reactor chamber and a reaction gasexhaust system 31 to exhaust reacted gases through the catalyst bed 21which is thermo-regulated by the heating element 3 and the coolingsystem 14 under the control of the temperature management system 5.

The gas flow system 15 allows loading the reaction gases (e.g. H₂ andCO₂, preferably a mixture thereof) within the gas loading zone 18 of thereactor chamber 12 through a reaction gas feeding system 17 and allowsexhausting the reacted gases (e.g. CH₄ and water vapor) from thecatalyzed reaction zone of the reactor chamber through a reaction gasexhaust system 31.

The cooling system comprises a cooling inlet for the coolant 23 (e.g.water, oil or other cooling medium) flow, a coolant circulation line 25,a coolant outlet 24 and a coolant flow controlling means 26. The coolantcirculation line 25 advantageously comprises a plurality of coolantcirculation channels (e.g. tubes) embedded in the reactor chamber 12 andpassing through the catalyst bed 21.

The temperature sensing system comprises temperature sensing elements invarious positions of the methanation reactor system, comprising thecooling system (inlet and out lets) and the reactor chamber, inparticular the catalyst bed to monitor the temperature of the reactorchamber during the methanation reaction.

The temperature management system 5 allows regulating the temperature ofthe reactor chamber 12 by regulating the temperature of the coolantentering the cooling system 14 though the cooling inlet 23 and its flowrate through the coolant circulation line(s) 25 and/or the flow spacevelocity of the reaction gases by regulating the flow rate reactionfeeding system 17 and thereby the loading of the reaction gases in thegas loading zone 18 of the reactor chamber 12.

Referring to FIG. 5, is illustrated in more details a gas flow system 15which comprises reaction gas feeding system 17 and reaction gas exhaustsystem 31 with pressure regulating elements (30 b and 30 c). The gasflow system may further comprise a purge gas feeding system 19 and apurge gas exhaust system 31 to flush purge gases (e.g. He, N₂) throughthe reactor chamber 12 for purging the reactor chamber or calibratingthe gas flow.

The pressure regulating elements of the gas flow system 30 b to e)allows controlling the reactor chamber pressure and maintaining itspressure lower than 10 bar, typically lower than 6 bar (e.g. 5 bar).

The cooling system 14 advantageously comprises a coolant exhaust system27 to allow controlling the cooling line pressure and maintaining itspressure lower than 5 bar, typically lower than 1.5 bar.

According to a particular aspect, the methanation reactor system furthercomprises a condenser system 7 on or after the reaction gas exhaustsystem 31 to eliminate water from the reacted gases by condensation.

As one can see, the reactor comprises a catalyst bed enclosed in areactor vessel. The catalysts preferably comprise at least one ofNickel, Cobalt and Ruthenium based catalysts, for example 20% wt.Ni/Al₂O₃ or 3% wt. Ru/Al₂O₃.

It also comprises one or several cooling tubes placed in the reactorvessel and passing through the catalyst bed and which are fed with acooling medium such as water, oil or any other fluid suitable for thispurpose. Preferably the cooling medium is at ambient Temperature whenfed in, but this is clearly not mandatory and it is possible to have anhomogeneous coolant temperature in the tubes or a serial arrangementwhere the temperature would be different in the different tubes.

The cooling tubes are disposed such that the temperature distribution inthe reactor shows large thermal gradients of at least 20° C./cm,preferably 100° C./cm, thereby generating hot spots throughout thereactor. The temperature gradients can be controlled by controllingeither the space velocity of the inlet reactant gases and/or the flowrate of the cooling medium.

This arrangement provides a combination of hot spots and colder zoneswithin a small volume what allows molecules to reach a high kineticenergy while maintaining the reaction equilibrium on the side of theproducts. Thus, a conversion higher than that achievable undernear-isothermal conditions is reached.

In order to maximize the reaction conversion, the minimal distancebetween the tubes should not be less than 1.5 times the tube diameter,or even better 2.0 times the tube diameter or more.

We will now describe the thermal management of the methanation reactorof the present invention. The thermal management of the methanationreactor has to address two issues: first, the reactor has to bepre-heated in order to start the reaction. Second, and as alreadymentioned, the methanation reaction is highly exothermic. Therefore, anadequate thermal management system has to be developed in order toeffectively remove the heat from the reaction zone and to control thetemperature of the chemical reactor.

As explained below, with this reactor, a conversion greater than 95% andeven greater than 99% in a single stage reactor has been experimentallymeasured.

The chemical reactor of the present invention can be used for anyexothermic reaction that is thermally limited. It is also particularlyadapted for the production of a mixture of water and methane from carbondioxide and hydrogen (Sabatier reaction). In any case, the applicationof this reactor is independent on the upstream (production of hydrogenand carbon dioxide) and downstream (use of the methane and water)processes.

The space velocity refers to the quotient of the entering volumetricflow rate of the reactants divided by the reactor volume which indicateshow many reactor volumes of feed can be treated in a unit time. Forexample, space velocity in a methanation process conducted according tothe invention can be from about 0.14 to about 0.55 s⁻¹ at a temperaturefrom about 150 to about 400° C. and at a pressure of the reactionchamber from about 1 to about 10 bar.

EXAMPLE

An example of the reactor and of its use will now be described.

In the present case, the target production was set to 100 g CH₄/hr. Thereactor was fed with a stoichiometric mixture of H₂ and CO₂, withnominal volumetric flows of 9.33 NI/min and 2.33 NI/min, respectively.The total power of the reactor amounted to around 2 kW, split in 1.54 kWcontained in the produced methane and 0.44 kW supplied in the form ofheat.

As a catalyst, a commercial ruthenium based catalyst was selected forthe chemical reactor. The catalyst was supplied by Sigma Aldrich and hasa 0.5% wt ruthenium loading on alumina. It is pressed in cylindricalpellets with an average diameter of 3.2 mm and a length of 5 mm. Thereactor bed is filled with 250 g of this catalyst to form a catalystbed. Transmission electron micrograph analysis (TEM, FEI, Tecnai G2spirit twin) was conducted in order to determine the particle size ofruthenium. Both new and used catalyst was measured, with no significantchange in the structure and particle size. The sample was prepared bymixing 0.01 g of sample in 1 mL ethanol for 30 min sonication anddispersing in carbon grid. The typical ruthenium particle size is in therange of 9-17 nm and the average size is 11.5 nm. This is slightlylarger than reported by Kwak et al., ACS Catalysis, 2013, who performedSTEM images of a similar catalyst (0.1% wt Ru on Al₂O₃) and foundruthenium particle sizes of up to 5 nm once the catalyst had been used.The average ruthenium particle size of 11.5 nm corresponds to a specificsurface area of 22.4 m²/g when considering spherical particles.

As an adequate thermal management system, a heating collar with a powerof 540 W and a maximal allowable temperature of 400° C. was installedaround the reactor tube in order to preheat the reaction zone atstartup. Further, the outer wall of the reactor tube was insulated suchthat the startup time is minimized.

The cooling of the reactor during operation was ensured by six coolingtubes embedded directly in the catalyst bed. The total heat generated inthe chemical reactor was calculated following equation (3) below.

QjB\=nHIJ ΔH.   (3)

Thereby, the value for the reaction enthalpy had to be calculated at thereaction conditions.

It was assumed that the reaction occurs above 140° C. and that waterexits the reactor in the vapor phase. Typically, the water condensatesoutside of the reactor. Therefore, the value for the reaction enthalpyunder operating conditions was calculated to 152 kJ/mol and the totalheating power of the reaction amounts to 264 W.

The maximal allowable thermal resistance given the existing thermalgradient between the reactor and the cooling fluid was computed and itcame out that dissipating such a high heat load by using air as thecooling medium required a fluid velocity of over 100 m/s in the coolingtubes, which is not realistic. Therefore, water was chosen as thecooling medium. A minimal water flow rate of 1.1 g/s was required tofulfill the thermal requirements.

Regarding the setup, the layout of the experimental setup is representedgraphically in FIG. 6. The gas stream of the reactants was controlled bytwo mass flow meters (Vögtlin Red—y Smart). A third gas line was builtin for helium or nitrogen, which can be used to flush the system or forcalibration purposes. The reactor was designed to operate attemperatures up to 400° C. and pressures up to 10 bar with a structuralsafety factor of 4. Pressure relief valves were installed on the maingas line and on the cooling loop to protect the system fromoverpressure. The flow rate of the cooling water was controlled by aproportional valve (Omega FSV 12). The exhaust stream of the reactor wascooled down in order to condensate the water. The composition of theremaining gases was analyzed in a Fourier Transformed InfraredSpectrometer (FT—IR, Alpha Bruker). Several pressure and temperaturesensors were embedded in the system to accurately monitor the testingconditions.

The reactor performance was tested under various conditions oftemperature and space velocity. For all experiments, the pressure wasset to 5 bar. From FIG. 1, it is seen that an increase in pressure past5 bar only leads to a marginal increase in the equilibrium conversion.Further, and from the point of view of implementation, CO2 fromatmospheric capture is available at low pressure. Thus, in order toavoid the use of an external compressor for the CO2, the reactorpressure is limited to 5 bar. The domain of investigation for the spacevelocity and the temperature was set to 0.14-0.55 s-1 and 140-400° C.These boundaries were defined to match the SSDS boundary conditions(quantity of methane produced), reactor limits (maximal temperature) aswell as thermodynamic modelling and literature review. A total of 57experiments were carried out in that domain. The calculated conversionare shown in FIG. 4.

The temperature shown as reactor temperature is only a representativevalue measured at a single point in the catalyst bed, as shown in FIG. 3(left). In practice, large temperature gradients are present in thereactor because of the local chemical reaction releasing heat and thecooling tubes going directly through the catalyst bed. It was indeedobserved that a temperature difference of almost 100° C. exists withinthe catalyst. In the actual reactor, this behavior is expected to beeven exacerbated due to inhomogeneous heat generation due to the spatialvariation of the chemical reaction rate within the reactor.

The reactor of the present invention proved to reach a very highconversion of up to 99% at a temperature set point of 260° C., apressure of 5 bar and a space velocity of 0.14 s-1.

A CO₂ conversion of 97% was reached at the target flow rate of 50 g/hr Hat a temperature set point of 280° C. It was found that the process islimited by the kinetics rather than the thermodynamic equilibrium underthe tested conditions. The obtained values are very close to—and in somecases even beyond—the theoretical thermodynamic equilibrium. This isexplained by the inhomogeneous temperature distribution in the chemicalreactor: while the temperature of the catalyst bed is measured at asingle point, there is a temperature distribution within the catalystbed enabling to balance both kinetics and equilibrium aspects. Finally,no degradation of the catalyst was observed after a period of fourmonths of usage.

While the embodiments have been described in conjunction with a numberof embodiments, it is evident that many alternatives, modifications andvariations would be or are apparent to those of ordinary skill in theapplicable arts. Accordingly, this disclosure is intended to embrace allsuch alternatives, modifications, equivalents and variations that arewithin the scope of this disclosure. This for example particularly thecase regarding the different apparatuses which can be used.

LIST OF ELEMENTS REFERENCED IN THE FIGURES

Methanation reactor system 1

-   -   Reactor vessel 2        -   Housing (air-tight, essentially cylindrical) 10            -   Reactor chamber 12                -   Gas mixture loading zone 18                -   Catalyzed reaction zone 20                -    Catalyst bed 21        -   Cooling system 14            -   Coolant inlet 23            -   Coolant outlet 24            -   Coolant circulation line 25            -   Coolant flow controlling means 26                -   Valve 30 a            -   Coolant exhaust system 27                -   Valve 30 b        -   Gas flow system 15            -   Reaction gas feeding system 17                -   Valve 30 c            -   Purge gas feeding system 19                -   Valve 30 d            -   Reaction gas exhaust system 31                -   Valve 30 e            -   Purge gas outlet system 32    -   Valve 30 f    -   Pressure sensing system 33    -   Heating element (coil) 3    -   Temperature sensing system 4    -   Temperature management system 5    -   Condenser 7

1-21. (canceled)
 22. A chemical reactor comprising a catalyst bedenclosed in a reactor vessel and at least one cooling tube placed in thereactor vessel and passing through the catalyst bed, characterized inthat the cooling tubes are disposed within the reactor so as to generatethermal gradients of at least 20° C./cm thereby generating hot spotsthroughout the reactor upon carrying out a reaction.
 23. The chemicalreactor according to claim 22, characterized in that the catalystscomprises at least one of nickel, cobalt and ruthenium based catalysts.24. The chemical reactor according to claim 22, characterized in thatthe catalysts comprises 20% wt. Ni/Al₂O₃ or 3% wt. Ru/Al₂O₃.
 25. Thechemical reactor according to claim 22, characterized in that itcomprises at least two cooling tubes.
 26. The chemical reactor accordingto claim 22, characterized in that the minimal distance between thetubes is not less than 1.5 times the tube diameter.
 27. The chemicalreactor according to claim 22, characterized in that the minimaldistance between the tubes is not less than 2 times the tube diameter.28. The chemical reactor according to claim 22, characterized in thatthe temperature of the cooling medium is different in the differenttubes.
 29. The chemical reactor according to claim 22, characterized inthat the tubes are fed with a cooling medium.
 30. The chemical reactoraccording to claim 22, characterized in that the thermal gradients areat least 100° C./cm.
 31. The chemical reactor according to claim 22,characterized in that the temperature gradients are controlled bycontrolling either the space velocity of the inlet reactant gases and/orthe flow rate of the cooling medium.
 32. The chemical reactor accordingto claim 31, characterized in that it further comprises a thermalmanagement system adapted to remove the heat from the reaction zone andto control the temperature of the chemical reactor.
 33. The chemicalreactor according to claim 22, characterized in that the reactor isadapted for exothermic chemical reaction.
 34. The chemical reactoraccording to claim 31, characterized in that it is a methanationreactor.
 35. A methanation reactor system including a reactor vesselcomprising a housing defining a reaction chamber comprising a gasloading zone and a catalyzed reaction zone; a cooling system; a gas flowsystem; a heating element in the vicinity of the reaction chamber; atemperature sensing system and a temperature management system, thecatalyzed reaction zone of the reaction chamber comprises a catalystbed, the cooling system comprises a plurality of coolant circulationlines within the catalyst bed, the gas flow system comprises a reactiongas feeding system configured to load reaction gases into the loadingzone of the reaction chamber and a reaction gas exhaust system toexhaust reacted gases through the catalyst bed which is thermo-regulatedby the heating element and the cooling system under the control of thetemperature management system.
 36. The methanation reactor according toclaim 35, wherein the cooling system comprises a cooling inlet for thecoolant flow, a coolant circulation line, a coolant outlet and a coolantflow controlling means.
 37. The methanation reactor according to claim35, wherein the cooling system further comprises a coolant exhaustsystem to allow controlling the cooling line pressure and maintainingits pressure lower than 5 bar or lower than 1.5 bar.
 38. The methanationreactor according to claim 35, wherein the gas flow system allowsloading the reaction gases within the gas loading zone of the reactionchamber through a reaction gas feeding system comprising pressureregulating elements and exhausting the reacted gases from the catalyzedreaction zone of the reaction chamber through a reaction gas exhaustsystem comprising pressure regulating elements.
 39. The methanationreactor according to claim 35, further comprising a condenser system onor after the reaction gas exhaust system to eliminate water bycondensation from the reacted gases.
 40. A method of production ofmethane from hydrogen and carbon dioxide comprising the steps of: a)providing a chemical reactor comprising a reaction chamber whichcomprises a gas loading zone and a catalyzed reaction zone comprising acatalyst bed; b) loading a reaction gas mixture of hydrogen and carbondioxide in the gas loading zone of the reaction chamber, such that thegas pressure in the reaction chamber is between 1 and 20 bar; c) heatingthe catalyst bed at a temperature between about 220 and about 260° C.such that the Sabatier reaction and a gas flow through the catalyst bedstarts; d) creating a temperature gradient of about 100° C. within thecatalyst bed by cooling the catalyst bed with a cooling system directlyintegrated in said catalyst bed; e) collecting the resulting gas mixtureflowing through the catalyst bed.
 41. The method according to claim 40,wherein the chemical reactor comprises a catalyst bed enclosed in areactor vessel and at least one cooling tube placed in the reactorvessel and passing through the catalyst bed, characterized in that thecooling tubes are disposed within the reactor so as to generate thermalgradients of at least 20° C./cm thereby generating hot spots throughoutthe reactor upon carrying out a reaction.
 42. The method according toclaim 40, wherein the chemical reactor is a methanation reactor systemcomprises a reactor vessel comprising a housing defining a reactionchamber comprising a gas loading zone and a catalyzed reaction zone; acooling system; a gas flow system; a heating element in the vicinity ofthe reaction chamber; a temperature sensing system and a temperaturemanagement system, the catalyzed reaction zone of the reaction chambercomprises a catalyst bed, the cooling system comprises a plurality ofcoolant circulation lines within the catalyst bed, the gas flow systemcomprises a reaction gas feeding system configured to load reactiongases into the loading zone of the reaction chamber and a reaction gasexhaust system to exhaust reacted gases through the catalyst bed whichis thermo-regulated by the heating element and the cooling system underthe control of the temperature management system.